What was found
ON FLIGHT 4259 (DTW TO PWM) RECEIVED FLAPS FAIL MESSAGE DURING FLIGHT WITH THE FLAPS EXTENDED AT ZERO DEGREE, AIRSPEED 195 KTS, OAT -19*C, NO SKEW DETECTION LIGHTS. CREW DECLARED EMERGENCY LANDING. PERFORMED TROUBLESHOOTING PER BOMBARDIER FIM REV 44 IAW AD 2009-06-12 PARAGRAOH (H)(6)(I) AMOC DATED DECEMBER 07-2012 AND PA AD 27-052J FECU CODES SHOWED BAD RT BPSU. REMOVED AND REPLACED RT BPSU IAW AMM 27-51-10. OPS CHECKS GOOD.